Low profile driver type golf club head

ABSTRACT

A metal wood golf club head of hollow construction incorporating a center of gravity (CG) depth of at least 40 mm, 1.57″, or greater, as measured rearwardly from the leading edge of the striking face, in combination with a shaft bore in the club head having a 0.370 bore diameter. The vertical height of the metal wood is half the club&#39;s breadth dimension between the front and rear of the club head and the vertical CG location is no greater than half the CG depth dimension. A bounce angle is incorporated into the leading portion of the bottom sole of the club head.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. Patent Application is a continuation in part of U.S. patent application Ser. No. 14/591,898 filed Jan. 7, 2017 entitled “Low Profile Driver Type Golf Club Head” the entire disclosure of the application being considered part of the disclosure of this application and hereby incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to golf clubs and in particular to metal wood type golf clubs that are used to hit golf shots with a tee and from the turf.

Drivers and fairway woods have evolved over the centuries. The first major changes to woods used to drive the ball occurred with the advent of the bulger driver. The low profile, long nose woods used to hit the feathery ball were no longer adequate with the introduction of the Haskell ball in the 1880's. The bulger woods, with their taller faces and narrower dimension from heel to toe, presented a superior design accommodation to strike the new generation of hard molded golf balls.

Few major geometry changes occurred in woods from the introduction of the bulger style driver in the 1880's until the late 1970's with the introduction of the first highly successful metal woods. Although metal woods were produced dating back to the late 1800's their popularity did not become mainstream until the late 1970's when PGA touring professionals began winning tournaments with them.

But just as wood design needed to advance with the ball evolution, today similar advancements in wood design are necessary to optimize ball flight using today's components, balls and fitting technologies.

The first generation of metal woods were investment cast stainless steel utilizing a pencil neck hosel and were slightly smaller than the wooden woods of the time. A typical driver used a 145 cc metal head volume and brought a novel aspect to the game. These were superb as a driving wood and were also manageable enough to be played from a good fairway lie by accomplished golfers. With the advent of the new hollow construction metal wood design, a larger shaft tip diameter accompanied these new metal woods providing greater tip stability to these new perimeter weighted heads. The previous solid wood construction drivers utilized a taper tip shaft averaging 0.294″ in diameter whereas the newer clubs used 0.335″ tip shafts.

The wooden clubs were completely solid and offered little forgiveness on miss-hits. However, the small head size of the newer metal woods appeared to be more forgiving, particularly on off-center impacts as compared to its wooden predecessor because the metal wood structure used a hollow perimeter, weighted head.

The next advancement in metal wood evolution took place as the head volume jumped from the mid 150 cc's to around 200 cc's. This size increase was novel at the time and while it showed itself to be an even more forgiving driver than the earlier generation, it took many golfers some time to adapt to the larger looking head. Those golfers with skill could still hit these 200 cc clubs from the fairway as well as off the tee.

The introduction of titanium as a head material followed and heads were introduced to the market around 260 cc in size as these “jumbo” sized drivers began gaining acceptance. Due to the larger footprint of the titanium heads the center of gravity became deeper than ever before and golfers experienced higher launch angles than in the past. These higher launch angles occurred using identical loft as the smaller drivers but because they possessed a deeper center of gravity (as measured from the leading edge of the face) the shaft experienced a forward bowing effect as the deep CG of the head aligns itself with the golfer's hands at impact. This physically increases the loft angle of the driver's face at impact resulting in a higher launch angle and often times greater back spin. Golfers appreciated this new style of driver performance. Acceptance was widespread and titanium quickly became the material of choice for nearly all manufacturers that were producing premium clubs.

Even though the head volumes had jumped from 145 cc to 200 cc and upwards of 260 cc golf manufacturers continued using 0.335″ tip shafts. Driver heads continued to increase in volume and as head sizes crossed the 300 cc threshold some golf companies began experimenting with a larger 0.350″ tip size for greater shaft stability. However, a 0.335″ tip size remained the norm.

As manufacturing technology continued to advance golf companies continued to design drivers in greater head volumes beyond 400 cc. Golf's governing bodies, the United States Golf Association (USGA) and the Royal & Ancient (R&A) Golf Society placed a head volume limit of 460 cc. This ruling occurred in 2003 and golf companies continue to maximize the size of their drivers to the 460 cc limit still assembled with a 0.335″ tip shaft.

As driver heads increased in size, the shaft companies became capable of producing shafts with stiffer tips and lower torque at both the 0.335″ and 0.350″ diameter sizes for metal woods.

In addition, as driver head volumes increased in size their CG depth continued to be positioned more rearward away from the face. Solid wood golf clubs had CG depths of 25 mm and the first generation of hollow steel (145 cc) drivers displayed similar CG depths of 24.5 mm. When the “oversize” steel drivers (200 cc) appeared, the CG depth grew slightly to 25.5. The first generation of titanium drivers (225 cc) displayed a CG depth of 27.0 mm.

The 300 cc drivers had CG depths of 31 mm-34 mm and 400 cc drivers gravitated to 35 mm-37 mm. As drivers began stabilizing at 460 cc the earlier generations of these maximum-sized heads offered CG depths of 37 mm-39 mm. However, through materials manipulation and geometry optimization some companies were able to increase driver CG depths up to 42 mm deep and greater.

CG Shaft Driver Model Volume Depth Tip Titliest Persimmon Driver 185 cc 25.5 .294″ Taylor Made Burner 153 cc 24.5 .335″ Founder Club Judge 200 cc 25.5 .335″ Oversize Founder Club Judge 225 cc 27.0 .335″ Titanium Callaway Biggest Big 300 cc 33.4 .335″ Bertha Titleist 983K 360 cc 32.2 .335″ Golfsmith HiCOR Plus 400 cc 37.3 .335″ Taylor Made SLDR 435 cc 33.3 .335″ Titleist 913DR 450 cc 40.5 .335″ Ping G400 460 cc 41.0 .335″

All the above listed drivers in the above table maintain a constant shaft tip diameter of 0.335″. Historically it is known that as the CG depth increases its influence on shaft dynamics is greater. A driver with a 42 mm deep CG will launch a golf ball higher and with greater spin versus the same size driver with a 35 mm CG depth using the same shaft. Golf companies have focused on a golf shaft's tip flex, balance point, weight and torque ratings to optimize ball flights associated with the changing CG depth locations. While shaft specs are important in optimizing a driver's performance it has become evident through component testing that a CG location and golf shaft tip diameter of a metal wood offer improved performance adjustment than focusing on altering specs within a 0.335″ tip shaft. While the larger tip 0.350″ shafts showed some promise in performance with heads exceeding 300 cc the golf industry eventually abandoned this tip diameter in preference for a “once size fits all” 0.335″ shaft tip. This became convenient for SKU management and product offerings but it has limited the club designer's potential of creating improved metal wood performance.

It followed that one of the few negative aspects of the jumbo titanium head designs was a lack of versatility away from the tee box. The driver head sizes become unwieldy when used to hit clean shots from the fairway. It essentially eliminated a club from the bag that previously was able to serve a dual purpose of being usable on both the tee box and fairway.

Golf club manufacturers continue to strive for deeper CG locations since a deeper CG typically goes hand-in-hand with a higher moment of inertia (MOI) clubhead that is more stable on off-center impacts. While the benefit of a deep CG can assist in increasing the launch angle at impact, the higher loft angle on the face often leads to increased back spin resulting in decreased overall distance that the golf ball travels.

A downside to a low and rearward CG location is that rear of the club head droops because of centrifugal force and adds loft to the striking face. This causes excessive spin and a higher launch angle and the travels a lesser distance.

Golfers with driver clubhead speeds in excess of 90 mph typically like to see the backspin reduced with their drives. A 90+mph clubhead speed is sufficient to get the ball airborne easily but too much backspin at a 90+mph head speed causes the ball rise or float depending on wind conditions and leads to a softer steeper landing with little roll. Reducing backspin for the same launch angle will result in a flatter apex and shallower angle of descent resulting in greater roll upon ground contact.

Golfers displaying slower driver clubhead speeds require more backspin to keep the ball in flight longer. The slower the clubhead speed the less velocity imparted to the ball. With the slower ball velocity backspin keeps the ball airborne for a longer carry.

There is a greater variance in specification targets for a 0.370″ shaft tip diameter as compared to a 0.335″ tip diameter. Those skilled in the art of graphite shaft design are aware that a larger shaft tip diameter can more easily be stabilized than a lesser tip diameter. More material is used in a 0.370″ tip versus a 0.335″ tip. This additional material can be used to stiffen the shaft tip, lower its torque, strengthen the shaft and dampen vibration at impact. Working in conjunction with a metal wood design incorporating a 40 mm CG depth and a wider tipped shaft of (0.370″) is more efficient in optimizing ball flight, launch conditions and off-center impact stability compared to a narrower 0.335″ tip.

A larger tip shaft (0.370″) can use intermediate and lower modulus rated carbon fiber to achieve similar torque ratings of a narrower tip shaft (0.335″). Yet to achieve the same torque on the 0.335″ shaft more expensive higher modulus carbon fiber must be used. Economics are benefited from the 0.370″ tip construction.

From a timing perspective the 0.370″ tip shaft takes longer to torque to its maximum point versus the 0.335″ tip shaft. If two different sized tip shafts have identical torque specifications, the larger tipped shaft will take longer to twist the same degree as the narrower tipped shaft. Ball contact on the face is 0.00047 seconds. An off-center impact with the 0.370″ shaft will have twisted less than the 0.335″ in the same impact conditions. The lower (and slower) torqueing of the 0.370″ tip shaft will result in a ball flight that is truer to the target line as the face of the club will be more squared at ball impact and a faster response is created to reduce spin allowing the ball to travel a greater distance.

There is a greater degree of shaft tip design variation in the larger 0.370″ tip construction. Coupled with marrying the shaft design to a CG depth 40 mm or greater provides greater optimization engineering based on the backspin requirements of the golfer.

2. Related Art SUMMARY OF THE INVENTION AND ADVANTAGES

The present invention is an improvement over prior art golf club heads that use rearward CG locations and 0.335 inch diameter golf shafts. The club head of the present invention provides greater optimal stability and superior gear effect and spin management to maximize driving distance. This is accomplished by a low-profile, metal wood club head having a CG location at least 40 mm deep, as measured from behind the leading edge of the club face, and having a vertical CG distance location from the bottom of the club head, no more than half the CG depth distance, in combination with a shaft opening of 0.370 inches, (9.4 mm), for connection to a 0.370, (9.4 mm) inch shaft.

The larger diameter shaft of 0.370 inches stabilizes the metal wood club head during impact against the golf ball because the larger shaft diameter prevents drooping of the rear of the club head and prevents an accompanying increase in loft of the striking face experienced with conventional drivers having a deep CG location but using a smaller diameter shaft. It follows the club head maintains launch angle control and spin management of the golf ball during its flight trajectory after being struck by the club head. The heretofore unknown combination of a low and deep, rearward CG location and large diameter shaft produces a new result of eliminating excessive spin and higher launch angles of the known prior art using a conventional 0.335 inch shaft tip.

A club head with a 0.370″ shaft tip displays similar launch conditions to a 0.335″ shaft tip but with lower spin and a flatter ball flight apex resulting in a shallower angle of descent to the ball flight as compared to a high launch angle with a high ball flight apex that results in a steep angle of descent leading to very little roll following the flight of the ball. By flattening out the ball flight's apex, the golf ball descends in a shallower angle with more velocity (energy) enabling the ball to run down the fairway for a longer distance for the drive.

The club head of this invention also uses a new, low profile, club head geometry has a vertical CG of 20 mm or lower, which is below the 21 mm equator of a golf ball. Maintaining a vertical CG in the club head that either matches or is lower than the ball's CG, results in shots hit from the turf easier to get airborne. Coupled with a very deep CG of 40 mm, or greater, this metal wood club head also provides a higher MOI resulting in more stability in the club head. These geometry ratios are novel and introduce new performance attributes to the invention not known in the prior art club heads.

The low-profile shape of the club head maintains a high MOI because its center of gravity is deep, rearward from the face, like on the jumbo drivers. At approximately 260 cc the present invention has a significantly smaller head making the club much easier to maneuver through the swing than a jumbo head. Also, at a volume of 260 cc, titanium is not required to produce the head. Less expensive stainless steel is a preferred metal and has the durability to meet performance requirements.

Another feature of the club head of the invention is a forward bounce area in the sole of the club. Drivers and fairway woods typically incorporate a sole with some form of radius running from front to rear. Coupled with cavities, ridges, steps and miscellaneous features the function of traditional driver soles has no physical effect or interaction with the turf in the execution of a golf shot. The forward bounce on this invention's sole provides dual benefits to a golf shot. When driving a golf ball from a tee, a first benefit enables a golfer to position the tee height low to the ground, as one would do for a fairway wood club, since the bounce on the sole allows the club head to contact the turf as the head comes to impact the ball.

Using bounce on a forward portion of the club head prevents the driver from digging into the tee box turf and assists in regulating a consistent vertical ball impact area on the face. Allowing the bounce of the club to contact the ground in concert with the low and rearward CG location causes a golfer to experience a more consistent swing plane as the face and ball impact heights are controlled by the bounce and tee respectively. Having a more consistent vertical impact between the driver and a ball, a more consistent launch angle will be experienced leading to overall driving consistency with this invention.

Another performance benefit of the bounce sole for a shot with a teed-up ball is that the angle of the bounce dynamically rotates the club face to a square position and then to a closed position once there is some ground contact. The lower the ball is teed, the more the sole bounce will rotate the face into a closed position. For golfers that lack the skill to square up a driver face, the club head of this invention will automatically close the face through physical dynamics between the club head and the turf.

Another benefit of this invention's bounce sole is the ability to use a driver from the fairway. As previous generations of head sizes at 300 cc's and above took away the flexibility to hit the driver from both the tee box and fairway, the bounce feature on this invention makes the driver versatile as a fairway club once again.

The bounce portion of the sole makes up approximately a quarter forward section of the club that makes ground contact and prevents the driver from digging into the turf. The bounce geometry promotes a sliding action through the turf and because its footprint represents a small portion of the sole there is less turf resistance than what would be experienced with a jumbo driver fairway shot.

The face of this invention is much shallower than contemporary drivers. Purposefully designed to be a low-profile fairway wood height, much of the weight associated with a driver face has been eliminated due to is low vertical profile and rather compact heel-to-toe dimension. The face is the heaviest part of a traditional driver design. This invention removes much of that weight providing a great deal of discretionary weight to be used to shift the center of gravity deeper, more rearward, behind the face and lower into the sole creating higher MOI and higher launch angles.

This invention introduces many novel performance benefits currently not available through a single type of pre-existing metal wood design. It is a high MOI head in a more compact package with a bounce sole regulating face impacts and launch angles in a versatile driver that can be easily hit from both the tee box and fairway. Assembled with a 0.370″ shaft tip optimization of launch and spin conditions are more efficiently achieved than with smaller tip “wood” shafts. Coupled with a thin lightweight face at the USGA/R&A coefficient of restitution limit the 260 cc design will play with the ease of a fairway wood but have the horsepower to impact maximum ball speed associated with jumbo heads.

Among the objects of the present invention is the provision of a driver type golf club head using a large diameter shaft opening in combination with a rearward and lower CG location.

Another object is the provision of a club head using a large diameter shaft opening in combination with a low-profile geometry, sole bounce and rear CG location.

Another object is the provision of a golf club that golfers of ordinary skill can use to hit a golf ball on a tee or lying on the ground.

These and other objects will become apparent with reference to the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of the club head of the present invention.

FIG. 2 is a top plan view of the club head of FIG. 1.

DESCRIPTION OF THE ENABLING EMBODIMENT

Referring to the drawings, a driver type, metal wood golf club head 100 is shown and includes a ball striking face 102, a top crown 104, heel 106, toe 108, side surfaces 110, a rear surface 112, bottom sole 114, forward bounce area 116, a leading edge 118 between the striking face 102 and bounce area 116 and a hosel 120 for connection to a golf shaft (not shown). The hosel 120 is formed with a shaft bore 122 that is 0.370 inches in diameter to accommodate and fit a complementary sized shaft having an outside diameter of 0.370 inches.

The breadth of the club head 100 is measured between the leading edge 118 of the striking face 102 and the rear surface 112. The width of the club head 100 is measured in a lateral direction between the heel 106 and toe 108 of the club head. The height between the top crown 104 and the bottom sole 114 is equal to or less than half the breadth of the club head 100 between the leading edge 118 and the rear surface 112.

The 0.370 inch diameter shaft bore 122 in the hosel 120 is cylindrical in shape to accommodate the tip end of a cylindrical golf shaft.

The bounce area 116 is located on the bottom sole 114 and forms approximately the forward one third to one quarter of the sole 114.

The striking face of a typical conventional golf club has more weight that the rest of the areas of the club head. In the present invention, the low-profile configuration of the club head 100 results in a thinner, shallower striking face 102 and shallow side surfaces 110. This weight distribution allows more weight to be located lower and rearwardly in the club head 100 and this weight configuration, in turn, locates the CG of the club head at least 40 mm to 45 mm behind the leading edge 118 of the striking face 102 and preferably as much as 47.5 mm behind the face 102. In addition, the CG is vertically located above the bottom sole 114 no more, and preferably less than, half of the distance the CG is located behind the leading edge 118 of the face 102. It follows, when the CG is 40 mm behind the face 102, the CG is no more than 20 mm in height from the bottom sole 114.

Because the CG location is low and rearward, this CG location causes the rear 112 of the club head 100 to droop downward due to the forces generated as the club is swung. The drooping of the head 100 causes the face 102 to rotate slightly in an upward direction thereby adding loft to the striking face 102. This upward gearing effect as the club head 100 is swung increases the spin rate of the golf ball when the face is contacted which greatly reduces in air flight distance of the ball and also reduces rollout once the ball impacts the ground or turf surface.

The wider, larger diameter golf shaft stabilizes the club head 100, reduces torque and substantially reduces the downward droop of the club head 100. This decreases the dwell time of the ball on the face 102 of the club head 100 thereby reducing the spin of the golf ball allowing the ball to travel further both in the air and on the ground.

In addition, the bounce area 116 of the club head 100 further stabilizes the club head 100 also reducing droop of the rear 112 resulting in increased ball flight and run-out when the ball hits the ground.

It will be appreciated that various modifications may be made in the golf club head of the present invention in keeping within the spirit and scope of the appended claims. 

What is claimed is:
 1. A driver type golf club head including a club head body formed of a top crown, heel, toe, side surfaces, rear surface, bottom sole and ball striking face where the improvement comprises: in combination, a shaft opening in said club head having an outside diameter of at least 0.370 inches, (9.4 mm), to accommodate a golf shaft; and, a center of gravity location of the club head being at least 40 mm rearward behind the leading edge of said striking face.
 2. The golf club of claim 1 wherein the height of the CG location above the bottom sole is no more than half of the distance that the CG is located behind the leading edge of the said ball striking face.
 3. The golf club of claim 1 including a hosel on an upper surface of said club head for connection to a golf shaft; said hosel having the shaft opening in the form of a cylindrical bore at least 0.370 inches diameter complementary with an outside diameter of the shaft.
 4. The golf club head of claim 1 further including a bounce area on said bottom sole extending rearwardly from said leading edge at an angle of at least three degrees below said bottom sole.
 5. The golf club head of claim 1 further defined by the CG location being at least 45 mm behind said face.
 6. A metal wood, driver type, golf club head including a hosel for connection with a golf shaft, a top crown, heel, toe, side surfaces, bottom sole, rear surface, a ball striking face between said top crown and said bottom sole, and a leading edge at the interface of said ball striking face and said bottom sole; wherein the improvement comprises: a shaft connection bore in said hosel having a diameter of at least 0.370 inches (9.4 mm); said shaft connection bore being complementary with in order to receive and locate an outside diameter of the golf shaft; said club head further defined by a center of gravity location at least 40 mm behind the leading edge of said striking face; a vertical height of the center of gravity location between the top crown and bottom sole being a no greater distance from the bottom sole than half of the distance that the CG is located behind the leading edge of the striking face; and, a bounce area on said bottom sole extending rearwardly from said leading edge at an angle of at least three degrees below said bottom sole. 